Electrode arrangement and method for coating flat workpieces with an electrically conductive layer and use of an electrode arrangement

Abstract

The invention relates to an electrode arrangement for coating flat workpieces with an electrically conductive layer, comprising at least two parallel flat electrodes (1a, 1b) and at least one spacer, wherein the two flat electrodes (1a, 1b) are spaced apart by the spacer and the spacer has at least one electrically insulating insulator area to prevent an electrically conductive connection between the flat electrodes through the spacer, wherein the spacer is arranged with one side against one of the two flat electrodes (1a, 1b) and with an opposite side against the other of the two flat electrodes (1a, 1b). Crucially, the spacer has at least one first shield (3a). wherein the first shield (3a) is arranged such that at least a partial area of ​​the insulator area is shielded by means of the first shield (3a), wherein the first shield (3a) is spaced apart from at least one of the surface electrodes (1a,1b) and wherein the spacer has a second shield (3b) which overlaps the first shield (3a), wherein the second shield (3b) is spaced apart from the first shield (3a) and the second shield (3b) is spaced apart from at least one of the surface electrodes (1a,1b), wherein the second shield (3b) overlaps the first shield (3a) in a direction perpendicular to the surface electrodes (1a, 1b), such that for particle currents parallel to the surface electrodes, the first shield (3a) is shielded by the second shield (3b). The invention further relates to a method for coating planar workpieces with an electrically conductive layer and to the use of an electrode arrangement.

Description

Description

[0001] The invention relates to an electrode arrangement and a method for coating planar workpieces with an electrically conductive layer according to the preambles of claims 1 and 11, and to the use of an electrode arrangement according to claim 13.

[0002] For coating flat workpieces, especially semiconductor devices, processes are known in which two oppositely polarized surface electrodes are used. One example of such a process is chemical vapor deposition (CVD), in particular plasma-enhanced chemical vapor deposition (PECVD).

[0003] When electrically conductive layers are deposited in such processes, a decrease in the efficiency of the deposition process, particularly the deposition rate, is observed with an increasing number of process runs, provided that insulating elements are exposed to the coating. Process stability can also be affected.

[0004] JP 2009-270161A proposes a device for producing a thin film on a substrate using a plasma-CVD process. The device comprises two electrodes separated by a spacer.

[0005] The invention is therefore based on the objective of avoiding or at least reducing a loss of efficiency in the deposition of electrically conductive layers and increasing process stability.

[0006] This problem is solved by an electrode arrangement for coating planar workpieces with an electrically conductive layer according to claim 1, a method for coating planar workpieces with an electrically conductive layer according to claim 11, and the use of an electrode arrangement according to claim 13.

[0007] Advantageous embodiments of the electrode arrangement according to the invention can be found in dependent claims 2 to 10 and of the method according to the invention in dependent claim 12.

[0008] The electrode arrangement according to the invention is preferably designed for carrying out the method according to the invention, in particular a preferred embodiment thereof. The method according to the invention is preferably designed for carrying out with the electrode arrangement according to the invention, in particular a preferred embodiment thereof.

[0009] It is known to use an electrode arrangement for coating flat workpieces with an electrically conductive layer, which has at least two parallel flat electrodes and at least one spacer. The two flat electrodes are spaced apart by the spacer.

[0010] The flat workpieces, in particular semiconductor wafers for the production of semiconductor devices, especially photovoltaic solar cells, are typically arranged on or attached to the flat electrodes. The flat electrodes are oppositely polarized, with the spacer being electrically non-conductive and preventing a short circuit between the oppositely polarized electrodes.

[0011] Investigations by the inventors show that during the deposition process, an electrically conductive layer is also deposited on the spacer, forming an electrically conductive connection between the parallel surface electrodes. With an increasing number of process cycles, the thickness of this layer increases, thus reducing the electrical resistance between the two parallel surface electrodes and consequently the potential difference between the oppositely polarized electrodes. This results in a decrease in the efficiency and / or process stability of the deposition process.

[0012] The electrode arrangement according to the invention for coating flat workpieces with an electrically conductive layer comprises at least two parallel flat electrodes and at least one spacer, wherein the two flat electrodes are spaced apart and electrically insulated by the spacer. The spacer is arranged with one side against one of the two flat electrodes and with an opposite side against the other of the two flat electrodes.

[0013] In the electrode arrangement according to the invention, it is essential that a spacer is used to separate the surface electrodes, wherein the spacer has at least one electrically insulating insulator area to prevent an electrically conductive connection of the surface electrodes through the spacer, wherein the spacer is arranged with one side on one of the two surface electrodes and with an opposite side on the other of the two surface electrodes.

[0014] The spacer has at least one first shield, wherein the first shield is arranged such that at least a partial area of ​​the insulator area is shielded by means of the first shield, wherein the first shield is spaced apart from at least one of the two surface electrodes.

[0015] In the electrode arrangement according to the invention, the permanent separation of the two surface electrodes is ensured by the electrically non-conductive spacer, which is arranged with one side against one of the two surface electrodes and with the opposite side against the other. It is not essential that the spacer be completely electrically non-conductive. However, the spacer must be electrically non-conductive in at least a partial area (insulator area) to prevent a short circuit between the two surface electrodes. Since the first shield is arranged such that at least a partial area of ​​the insulator area is shielded by the first shield, coating of the electrically non-conductive area of ​​the spacer is avoided, or at least the deposition rate is significantly reduced by the first shield.

[0016] Furthermore, the first shield is spaced away from at least one of the two surface electrodes. Even if an electrically conductive layer is deposited on the surface of the first shield, this ensures that a short circuit between the two surface electrodes is not formed by a potentially electrically conductive first shield, since the shield is spaced away from at least one of the two surface electrodes.

[0017] The problem initially posed is further solved by a method for coating flat workpieces with an electrically conductive layer. The method according to the invention comprises the following process steps: A. Providing at least two parallel surface electrodes, which are spaced apart from each other by at least one spacer; B. Arranging at least one workpiece on at least one surface electrode; C. Forming an alternating electric field between the electrodes and coating the workpieces with an electrically conductive layer;

[0018] A spacer is used to separate the surface electrodes, wherein the spacer has at least one electrically insulating insulator area to prevent an electrically conductive connection of the surface electrodes through the spacer, wherein the spacer is arranged with one side on one of the two surface electrodes and with an opposite side on the other of the two surface electrodes.

[0019] The spacer has at least one first shield, wherein the first shield is arranged such that at least a portion of the insulator area is shielded by the first shield, and wherein the first shield is spaced apart from at least one of the two surface electrodes. The spacer has a second shield, the second shield overlapping the first shield, the second shielding being spaced apart from the first shielding, and the second shielding being spaced apart from at least one surface electrode.

[0020] It is essential that the second shield overlaps with the first shield in a direction perpendicular to the surface electrodes, such that for particle currents parallel to the surface electrodes the first shield is shielded by the second shield.

[0021] This results in the advantages mentioned for the spacer according to the invention; in particular, the risk of an electrically conductive layer forming on the spacer between the surface electrodes is avoided or at least significantly reduced.

[0022] The shielding, comprising the first and second shields, thus fulfills the essential function of preventing or at least reducing the flow of particles used in the coating process to the shielded insulator area during the coating process. The shielding is therefore preferably arranged on an outer side of the insulator area. In particular, it is advantageous that the shielding encompasses the insulator area in a cross-sectional plane parallel to the surface electrodes.

[0023] In an advantageous embodiment, the spacer and the first shield form a channel. This reduces the particle flux to the surface of the spacer within the channel and thus reduces the risk of an electrically conductive layer forming on the inner walls of the channel. It is particularly advantageous that the channel is closed at one end, so that the formation of a particle flux penetrating the channel is avoided or at least the flux rate of such a flux is significantly reduced.

[0024] In an advantageous embodiment, the first and / or second shielding overlaps with the insulator area of ​​the spacer.

[0025] This has the advantage that in the overlap area a particle flow and thus the formation of an electrically conductive layer is avoided, or at least the formation rate is significantly reduced.

[0026] Advantageously, the first and / or second shield overlaps with an electrically non-conductive insulator area of ​​the spacer in a direction perpendicular to the surface electrodes. This shields the electrically non-conductive area of ​​the spacer from the particle stream, at least for particle streams moving parallel to the surface electrodes, thus preventing coating or at least reducing the coating rate.

[0027] To avoid a particle flow between the first shield and the electrically non-conductive insulator area of ​​the spacer, or at least to reduce the number of particles or the flow rate, it is advantageous that the distance between the first shield and the insulator area is < 10 mm, preferably < 1 mm, and particularly preferably < 0.5 mm.

[0028] To avoid contact between the first shield and the insulator area, especially in the case of any coating, or at least to reduce the risk thereof, it is advantageous that the distance between the first shield and the insulator area is > 0.01 mm, preferably > 0.05 mm.

[0029] Alternatively or preferably additionally, it is advantageous to reduce the particle flux between the first and / or second shielding and the insulator area by making the distance between the first and / or second shielding and the surface electrode < 10 mm, preferably < 1 mm, particularly preferably < 0.5 mm.

[0030] A small distance between the shield and the surface electrode thus avoids or reduces a particle current between the first and / or second shield and the surface electrode into the space between the first and / or second shield and the insulator area.

[0031] In the case of any coating of the first shield and / or the surface electrode, and due to tolerances in material expansion, it is advantageous that the distance between the first shield and the surface electrode is > 0.01 mm, preferably > 0.05 mm. This also reduces the risk of an electrical flashover between the first shield and the surface electrode.

[0032] In an advantageous embodiment, the first shield extends at least to the insulator area of ​​the spacer. This has the advantage that, in the portion of the insulator area adjacent to the first shield, the formation of an electrically conductive layer is avoided in a particularly efficient manner, or at least such a risk is significantly reduced.

[0033] In an advantageously simple design, the first and / or second shield is cylindrical, preferably circular cylindrical.

[0034] Alternatively or preferably additionally, for a structurally simple design, the insulator area is cylindrical, preferably circular cylindrical.

[0035] Alternatively or preferably additionally, for a structurally simple design, the spacer is cylindrical, preferably circular cylindrical.

[0036] The cylinder axis of the first and / or second shielding and / or spacer, preferably of the first and second shielding and the insulator area, is preferably arranged perpendicular to the surface electrodes.

[0037] To prevent contact between the insulator and the first shield, particularly in the event of mechanical stress on the first shield, it is advantageous to arrange a support element between the first shield and the insulator area. The support element is preferably electrically non-conductive.

[0038] The risk of coating the electrically non-conductive area of ​​the spacer is further reduced by the spacer according to the invention having a second shield. The second shield overlaps the first shield and is spaced apart from it. Furthermore, the second shield is spaced apart from at least one surface electrode.

[0039] The second shield thus prevents or at least reduces particle flow to the first shield. By spacing the second shield from at least one surface electrode, an electrical short circuit between the surface electrodes is prevented by the second shield, just as with the first shield.

[0040] It is essential that the second shield overlaps with the first shield in a direction perpendicular to the surface electrodes, such that for particle currents parallel to the surface electrodes the first shield is shielded by the second shield.

[0041] The distance between the second shield and the first shield is preferably < 10 mm, preferably < 1 mm, particularly preferably < 0.5 mm, in order to reduce particle flux as described for the first shield.

[0042] The distance between the second shield and the surface electrode is preferably > 0.01 mm, preferably > 0.05 mm. This prevents – as already described for the first shield – an electrically conductive connection and also an electrical flashover between the second shield and the surface electrode.

[0043] The connection between the surface electrodes and the spacer is preferably achieved by means of a guide rod, in particular a straight guide rod. Advantageously, the spacer and the surface electrodes therefore have recesses (guides) to allow the straight guide rod to pass through the recesses.

[0044] Advantageously, a plurality of electrode arrangements are stacked one above the other, such that the electrode arrangement comprises a plurality of surface electrodes, preferably at least five, more preferably at least ten surface electrodes, wherein at least one spacer as described above, with an electrically non-conductive insulator section and a first and / or second shield, is arranged between each pair of adjacent surface electrodes. In particular, it is advantageous to arrange several spacers, each with an electrically non-conductive insulator section and a first and / or second shield as described above, between two adjacent surface electrodes for stabilization. Advantageously, the electrode arrangement is stabilized by one or preferably several straight guide rods, which penetrate the surface electrodes and the spacers perpendicular to the surface electrodes.

[0045] It is within the scope of the invention that the spacer is formed in one piece, in particular completely electrically non-conductive.

[0046] It is also within the scope of the invention that the spacer is designed in multiple layers, with one or more electrically non-conductive layers. It is also within the scope of the invention that the spacer also has electrically conductive sections, in particular electrically conductive layers.

[0047] It is essential that there is no electrically conductive connection between the contact points of the spacer with the first and second of the two surface electrodes.

[0048] In an advantageous embodiment, the insulator area is formed from multi-part elements.

[0049] It is particularly advantageous that the insulator area comprises a base plate and a support element with a smaller circumference than the base plate. This makes it structurally simple to arrange the first shielding on or against the base plate, and in particular, to form the first shielding integrally with the base plate. Within the scope of the invention, the base plate, the support element, or preferably the base plate and the support element are electrically non-conductive and made of ceramic, preferably fired ceramic.

[0050] Advantageously, the support element and the first shielding are thus arranged on the base plate.

[0051] In the advantageous embodiment described above, in which the spacer has a base plate and a support element, the base plate or the support element, in particular the base plate and the support element, are preferably made of ceramic, preferably of fired ceramic.

[0052] The method according to the invention is particularly advantageous if, in an advantageous embodiment, deposition takes place in an electric field in process step C and a coating of the insulating element between the surface electrodes cannot be ruled out.

[0053] In an advantageous embodiment of the process according to the invention, the coating is preferably carried out in process step C by means of chemical vapor deposition (CVD), and in particular preferably by means of plasma-enhanced chemical vapor deposition (PECVD). For a large number of deposition processes, the use of a PECVD process is advantageous because only in this way can a desired layer thickness be achieved or the thermal stress be kept low. This is particularly true because gas exchange is reduced in the shielded area, thereby preventing or at least making the formation of a plasma less likely.

[0054] Likewise, it is within the scope of the invention that, in an advantageous embodiment, in process step C a coating is carried out by means of physical vapor deposition (PVD), in particular by means of sputtering or vapor deposition with the formation of an electric field between the surface electrodes.

[0055] The aforementioned problem is further solved by the use of an electrode arrangement, in particular an electrode arrangement according to the invention, preferably an advantageous embodiment thereof, for coating a workpiece, in particular by means of chemical vapor deposition.

[0056] For a structurally simple design, it is advantageous that the first and / or second shield is designed as a rotationally symmetric body.

[0057] Alternatively or preferably additionally, it is advantageous for the support element to be designed as a rotationally symmetric body.

[0058] Further advantageous features and designs are described below with reference to exemplary embodiments and the figures. These show: Fig. 1. A first exemplary example of a spacer; Fig. 2 a second exemplary example of a spacer with guide; Fig. 3 a third embodiment of a spacer according to the invention with two shields; Fig. 4 a fourth embodiment of a spacer according to the invention with three shields; Fig. 5 a fifth exemplary example of a spacer with two fastening elements for the first shielding; Fig. 6 a sixth exemplary example of a spacer with base plate groove fastening for the first shielding; Fig. 7 a seventh exemplary example of a spacer with two opposing shields; Fig. 8 an eighth exemplary example of a spacer with a conical support element; Fig. 9 a ninth exemplary example of a spacer with a conical support element; Fig. 10. A tenth exemplary example of a spacer with flange as a shielding attachment.

[0059] All figures are schematic representations, not to scale. Identical reference symbols within the figures denote identical or similarly functioning elements.

[0060] In the Fig. 3 and Fig. Figure 4 shows exemplary embodiments of a spacer according to the invention. Fig. 1 and Fig. 2 as well as in the Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. Figure 10 shows examples of a spacer. The first figure in each figure shows the spacer and the surface electrodes in a frontal view. The second figure shows the spacer and the surface electrodes in section along the dashed section line of the first figure. The third figure shows a top view of the spacer without the surface electrodes positioned above and below it.

[0061] Fig. Figure 1 shows a first exemplary electrode arrangement for coating flat workpieces with an electrically conductive layer, in this case for coating silicon wafers in the production of photovoltaic solar cells using a PECVD process. For this purpose, the silicon wafers are placed on the flat electrode below.

[0062] The spacer shown in Fig. 1 is arranged between a first surface electrode 1a and a second surface electrode 1b, which are arranged parallel to each other.

[0063] In this embodiment, the spacer is made up of several parts. The spacer comprises an electrically non-conductive circular base plate 6 and an electrically non-conductive cylindrical support element 2. The support element 2 has a smaller diameter than the base plate. The base plate 6 rests flat on the surface electrode 1b. The support element 2 is arranged in the center of the upper surface of the base plate. In this embodiment, the base plate 6 and the support element 2 are made of ceramic, specifically fired ceramic. The circular upper surface of the cylindrical support element 2 rests against the surface electrode 1a. In this embodiment, the shield 3 is designed in the shape of a sleeve. This sleeve shape has the same outer diameter as the base plate 6. The shield 3 is arranged concentrically on the base plate 6.The shielding 3 arranged on the base plate 6 is spaced from the surface electrode 1a by a distance d2. In this embodiment, the distance d2 between the shielding 3 and the surface electrode 1a is less than 10 mm, in this case 1 mm.

[0064] The shielding and the support element 2 are separated by a distance d1. In this embodiment, the distance d1 between the shielding 3 and the electrically non-conductive area of ​​the support element 2 is less than 10 mm and greater than 0.01 mm, in this case 0.5 mm.

[0065] The shielding overlaps with the electrically non-conductive insulator area of ​​the spacer in a direction perpendicular to the surface electrodes in the area u1 and the shielding extends at least to the electrically non-conductive insulator area of ​​the spacer, in this case to the base plate 6.

[0066] This creates an annular channel bounded by the outer surface of the support element 2 and the inner surface of the shielding 3. The annular channel is closed at the bottom by the base plate 6. This partially closed annular channel reduces the risk of a layer forming during the coating process on the outer surface of the support element 2 in the overlap area u1 and, in particular, at the closed end of the annular channel on the exposed upper surface of the base plate 6. The insulating function of these insulator areas (outer surface of the support element 2 in the overlap area and exposed upper surface of the base plate 6) is therefore not, or only minimally, affected by the formation of an electrically conductive layer during the coating process.

[0067] Variations of the illustrated embodiment show: - the element has 2 conductive, the shielding 3 conductive and the base plate 6 non-conductive electrical properties; - the element 2 has conductive, the shielding 3 has non-conductive and the base plate 6 has non-conductive electrical properties.

[0068] Furthermore, in a modification of the illustrated embodiment, the base plate 6 can be formed integrally with the shielding 3, or the spacer can be made integrally; in this case, the integrally made spacer must be electrically non-conductive.

[0069] In Fig. Figure 2 shows another exemplary example, in which the first exemplary example has been extended by a guide. The guide 7 runs vertically through the center of the cylindrically shaped spacer.

[0070] The spacer, equipped with guide 7, is positioned with one side against one of the two surface electrodes and with the opposite side against the other of the two surface electrodes. In this embodiment, the surface electrodes are also provided with guides 7a and 7b (surface electrode guides). The guides 7 of the spacer and the surface electrodes are aligned. The spacer guide and the surface electrode guide have the same guide diameter. The guides are advantageous in this example because they allow a guide rod to pass through the spacer and through the surface electrodes.

[0071] The guide rods center the elements concentrically around the spacer's center point. Thus, the distance d1 remains constant throughout the circumference. The functions and variations of the first example can be transferred to the version with guides.

[0072] This exemplary example with guides is intended to be representative of all cylindrically shaped spacers of the following embodiments: In this embodiment as well, guides for a guide rod are advantageously provided.

[0073] In the Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. 7 are further examples of implementation ( Fig. 3 and Fig. 4) and exemplary examples ( Fig. 4, Fig. 5, Fig. 6 to Fig. 7) a spacer, which in most of its technical features corresponds to the one described in the Fig. The first exemplary example shown in point 1 is consistent with this. To avoid repetition, the main differences in the explanations are outlined below:

[0074] Fig. Figure 3 shows an embodiment of a spacer according to the invention which has two shields. In this embodiment, the second shield 3b is designed as a sleeve with a cover plate, which is arranged concentrically over the support element 2, such that the cover plate rests against the inside of the support element 2 and the outside of the cover plate rests against the surface electrode 1a, and the sleeve shell runs parallel to the support element shell. The diameter of the second shield 3b is smaller than that of the first shield 3a and is larger than the diameter of the support element 2.

[0075] The first shield 3a overlaps the second shield 3b of the spacer and the electrically non-conductive insulator area of ​​the spacer in a direction perpendicular to the surface electrodes u1. The second shield 3b overlaps the electrically non-conductive insulator area of ​​the spacer in a direction perpendicular to the surface electrodes u2.

[0076] The shield 3b is spaced apart from the surface electrode 1b, the first shield 3a is spaced apart from the surface electrode 1a.

[0077] This creates a winding channel, closed on one side. Due to the opposite side in Fig. 1. By increasing the length of the channel, the risk of the formation of an electrically conductive layer on the outside of the support element 2 in the overlap area u2 is further reduced.

[0078] In Fig. Figure 4 shows an embodiment of a spacer according to the invention with three shields. In this embodiment, the third shield 3c is a second sleeve on a cover plate according to embodiment three. Fig. 3, which is arranged concentrically over the support element 2, so that the cover plate rests on the inside of the support element 2 and the outside of the cover plate rests on the surface electrode 1a and the sleeve shell runs parallel to the support element shell.

[0079] The diameter of the third shield 3c is larger than that of the first shield 3a and second shield 3b and is larger than the diameter of the support element 2. The third shield 3c overlaps the second shield 3b, the first shield 3 of the spacer, and the electrically non-conductive insulator area of ​​the spacer in a direction perpendicular to the surface electrodes u3. The first shield 3a overlaps the second shield 3b and the electrically non-conductive insulator area of ​​the spacer in a direction perpendicular to the surface electrodes u1. The second shield 3b overlaps the electrically non-conductive support element 2 of the spacer in a direction perpendicular to the surface electrodes u2.

[0080] The second shield 3b and the third shield 3c are spaced apart from the surface electrode 1b, and the first shield 3a is spaced apart from the surface electrode 1a. The spacing of the shields from each other and from the support element 2 results in a channel formation that is bounded by the lateral surfaces of the shields, the support element 2, and the base / top plate.

[0081] This increases the channel length to the overlap area u3 on the outside of the support element 2 compared to the one in Fig. The embodiment shown in 3 is extended again.

[0082] The exemplary example, which is in Fig. Figure 5 shows a spacer with two fastening elements 4a, 4b for fixing the shielding 3.

[0083] The spacer is positioned with one side against one of the two surface electrodes and with the opposite side against the other. In this example, the support element 2 is positioned between the two surface electrodes. The fastening elements 4a and 4b, which are connected to the shield 3, are attached to the support element 2 at half its height. The shield 3 is held at a distance d1 from the support element 2 by means of the fastening elements 4a and 4b. The shield 3 overlaps the electrically non-conductive support element 2 of the spacer in a direction u1 perpendicular to the surface electrodes.

[0084] The shield 3 is spaced apart from the surface electrode 1b and from the surface electrode 1a. In this exemplary configuration, the spacing between the shield 3 and the support element 2 forms a channel that is only delimited by the support element 2 and the shield 3. In this exemplary configuration, the support element 2 must be electrically non-conductive; the shield 3 and the fastening elements can be either conductive or non-conductive.

[0085] In this exemplary case, a ring channel open at both ends is formed. In the overlap area u1, particularly in the center of the area of ​​the fastening elements 4a and 4b, the shielding prevents the formation of an electrically conductive layer during the coating process or at least significantly reduces its formation rate.

[0086] Another way of fixing the shield is shown in the exemplary example in Fig. Figure 6 shows that the base plate 6 has an annular groove. The thickness of the groove is chosen such that the shielding element 3 can be fixed in the base plate via the annular groove. In this embodiment, the groove is at least thick enough to allow the shielding element to pass through it. The shielding properties correspond to those of the first exemplary example.

[0087] In Fig. Figure 7 shows a seventh exemplary example. This example shows a spacer with two shields 3a and 3b, which are positioned opposite each other and overlap a portion of the support element 2 by a distance d1. The difference from the previous examples is that the shields 3a and 3b are equidistant from the support element 2 and therefore have the same diameter. Furthermore, the first shield 3a is sleeve-shaped and attached to a cover plate, as in exemplary example three. Fig. 3 attached, which is concentrically mounted on the top of the support element and rests against the surface electrode 1a with the top of the cover plate.

[0088] The second shield 3b is also sleeve-shaped and attached to a base plate as in embodiment three. Fig. 3 attached, which is concentrically mounted on the underside of the support element and rests against the surface electrode 1b with the underside of the base plate.

[0089] The first shield 3a does not overlap with the shield 3b, but overlaps with the electrically non-conductive insulator area of ​​the spacer in a direction u1 perpendicular to the surface electrodes.

[0090] The second shield 3b does not overlap with the first shield 3a, but overlaps with the electrically non-conductive insulator area of ​​the spacer in a direction u2 perpendicular to the surface electrodes.

[0091] The second shield 3b is spaced apart from the surface electrode 1a, and the first shield 3a is spaced apart from the surface electrode 1b. The vertical spacing of the shields to each other and the spacing to the support element 2 result in a channel formation that is bounded by the lateral surfaces of the shields, the support element 2, and the base / top plate.

[0092] The formation of an electrically conductive layer on the outside of the support element 2 in the overlap areas u1 and u2 and especially at the closed ends of the two ring channels at the upper and lower ends of the support element 2 is thus avoided or at least the deposition rate is significantly reduced.

[0093] The eighth exemplary example in Fig. Figure 8 shows a spacer that differs from the previous examples in that it has a partially conical support element 2 with a spherical protrusion at its tip. The base of the partially conical support element 2 is located on the surface electrode 1b. The counterpart of the partially conical support element 2, designed as a shield 3, has a conical recess with the same conical taper as the support element 2. The shield 3 is positioned such that the conical part of the support element 2 leads into the conical recess of the shield. The spherical protrusion of the support element 2 results in a distance d1. The shield 3 is therefore only in contact with the support element 2 over a portion of the spherical protrusion of the support element 2. Thus, the shield 3 extends at least to the electrically non-conductive insulator area of ​​the spacer.The upper side of the shielding 3 is arranged on the surface electrode 1a.

[0094] The spacing between the shielding 3 and the support element 2 results in a channel formation that is bounded by the conical surfaces of the shielding and the support element 2, as well as by the surface of the spherical bulge in the support element 2. The shielding 3 overlaps the electrically non-conductive insulator area of ​​the spacer in a direction u1 perpendicular to the surface electrodes.

[0095] During the coating process, the formation of an electrically conductive layer on the outside of the conical area of ​​the support element 2 is thus avoided, particularly in the upper area, or at least the deposition rate is significantly reduced.

[0096] In Fig. Figure 9 shows another exemplary example of a spacer; this example consists of three parts. The three elements have identical geometries. The geometry of one element can be described by a truncated cone with a frustoconical recess. The recess allows the frustoconical elements to be stacked inside one another.

[0097] The concentrically stacked frustoconical elements form a guide 7. The guide 7 runs perpendicularly through the center point of the frustoconical elements, which form the spacer (spacer guide). The spacer, equipped with the guide 7, is positioned with one side against one of the two surface electrodes and with the opposite side against the other of the two surface electrodes. In this embodiment, the surface electrodes are also provided with guides 7a and 7b (surface electrode guides). The spacer guide and the surface electrode guide are aligned. In this embodiment, the guide diameter is selected such that the spacer guide and the surface electrode guide have the same diameter. The guides are advantageous in this example because they allow a guide rod to be guided through the spacer and through the surface electrodes.The guide rods center the elements concentrically around the spacer center point.

[0098] In this exemplary case, the top element is electrically non-conductive and thus forms the support element 2. The middle element 3a and the bottom element 3b therefore act as shields. Because the top surface of the frustoconical recess has a larger diameter than the top surface of the frustocone, the distances d1 and d2 result when the elements are stacked.

[0099] The distances d1 and d2 thus describe the difference in radii between the truncated cone and the truncated cone-shaped recess along the tapering path. This distance remains constant when two elements overlap because the degree of tapering at the truncated cone-shaped recess and the truncated cone is constant. Therefore, the outer surface of the truncated cone-shaped recess of one element, together with the outer surface of the second element and part of the top surface of the truncated cone-shaped recess, forms a channel.

[0100] The second shield 3b and the first shield 3a are spaced apart from the surface electrode 1a, the shield 3a is also spaced apart from the surface electrode 1b.

[0101] Shielding 3a overlaps shielding 3b and the electrically non-conductive support element 2 of the spacer in a direction perpendicular to the surface electrodes u1. Shielding 3a overlaps the electrically non-conductive support element 2 of the spacer in a direction perpendicular to the surface electrodes u2. Shielding 3a extends at least to the electrically non-conductive insulator area of ​​the spacer.

[0102] For the device to function as a spacer according to the invention, at least one element of the illustrated example must be electrically non-conductive or at least have an electrically non-conductive insulator area that is shielded by part of a shield. In the present case, all three elements are made of electrically non-conductive ceramic.

[0103] The Fig. Figure 10 shows an exemplary example of a spacer with a shielding attachment. In this example, the shielding 3 is attached to the surface electrode 1b via a flange 5. The flange 5, in particular a loose flange, is provided with bores, as is the surface electrode 1b. Screws are passed through these bores and, with nuts, in particular locknuts, serve to attach the shielding to the surface electrode. In this embodiment, the spacer has the same properties as in the first embodiment shown in Figure 10. Fig. 1 shown. Reference symbol list 1a first surface electrode 1b second surface electrode 2 support elements 3 Shielding 3a first shielding 3b second shielding 3c third shield 4 retaining elements 5 flange 6 Base plate 7 Leadership 7a first surface electrode guide 7b second surface electrode guide

Claims

[1] Electrode arrangement for coating flat workpieces with an electrically conductive layer, with at least two parallel surface electrodes (1a,1b) and at least one spacer, wherein the two surface electrodes (1a,1b) are spaced apart by the spacer and the spacer has at least one electrically insulating insulator area to prevent an electrically conductive connection of the surface electrodes through the spacer, wherein the spacer is arranged with one side on one of the two surface electrodes (1a,1b) and with an opposite side on the other of the two surface electrodes (1a,1b), where the spacer has at least one first shield (3a), wherein the first shield (3a) is arranged such that at least a partial area of ​​the insulator area is shielded by means of the first shield (3a) and wherein the first shield (3a) is spaced apart from at least one of the two surface electrodes (1a,1b), wherein the spacer has a second shield (3b), the second shield (3b) overlaps with the first shield (3a), the second shield (3b) is spaced apart from the first shield (3a) and the second shield (3b) is spaced at least apart from one of the surface electrodes (1a,1b), wherein the second shield (3b) overlaps with the first shield (3a) in a direction perpendicular to the surface electrodes (1a,1b) such that for particle currents parallel to the surface electrodes the first shield (3a) is shielded by the second shield (3b). [2] Electrode arrangement according to claim 1, characterized by, that the first and / or second shielding (3a, 3b) overlaps with the insulator area of ​​the spacer, in particular in a direction perpendicular to the surface electrodes (1a,1b). [3] Electrode arrangement according to claim one of the preceding claims, characterized by , that the first and / or second shielding (3a, 3b) extends at least to the insulator area of ​​the spacer. [4] Electrode arrangement according to claim one of the preceding claims, characterized by , that the distance between the first shielding (3a) and the insulator area is less than 10 mm, preferably less than 1 mm, particularly preferably less than 0.5 mm and / or that the distance between the first shield (3a) and the insulator area is greater than 0.01 mm, preferably greater than 0.05 mm. [5] Electrode arrangement according to claim one of the preceding claims, characterized by , that the distance between the first shield (3a) and the surface electrode (1a,1b) is less than 10 mm, preferably less than 1 mm, particularly preferably less than 0.5 mm and / or that the distance between the first shield (3a) and the surface electrode (1a,1b) is greater than 0.01 mm, preferably greater than 0.05 mm. [6] Electrode arrangement according to claim one of the preceding claims, characterized by , that the spacer and the surface electrodes (1a,1b) have guides (7,7a,7b) to arrange a straight guide rod penetrating the guides (7,7a,7b). [7] Electrode arrangement according to claim one of the preceding claims, characterized by that the spacer is multi-part. [8] Electrode arrangement according to claim 7, characterized by , that the spacer has a plate, preferably a base plate (6) in particular a top plate and a support element (2) with a smaller circumference than the plate, preferably a base plate (6) in particular a top plate, in particular, that the support element (2) and the first shielding (3a) are arranged on the plate, preferably base plate (6) in particular cover plate. [9] Electrode arrangement according to claim one of the preceding claims, characterized by , that the spacer has an electrically non-conductive support element (2) which is made of ceramic, preferably fired ceramic. [10] Electrode arrangement according to claim one of the preceding claims, characterized by , that the spacer and the first shield (3a) form a channel which is preferably closed on one side. [11] Method for coating planar workpieces with an electrically conductive layer, comprising the process steps A. Providing at least two parallel surface electrodes (1a,1b) spaced apart from each other by at least one spacer; B. Arranging at least one workpiece on at least one surface electrode (1a,1b); C. Forming an alternating electric field between the surface electrodes (1a,1b) and coating the workpieces with an electrically conductive layer; wherein a spacer is used which has at least one electrically insulating insulator area to prevent an electrically conductive connection of the surface electrodes through the spacer and the spacer is arranged with one side on one of the two surface electrodes (1a,1b) and with an opposite side on the other of the two surface electrodes (1a,1b), wherein the spacer has at least one first shield (3a), wherein the first shield (3a) is arranged such that at least a part of the insulator area is shielded by means of the first shield (3a), wherein the first shield (3a) is spaced apart from at least one of the two surface electrodes (1a,1b), wherein the spacer has a second shield (3b), the second shield (3b) overlaps with the first shield (3a), the second shield (3b) is spaced apart from the first shield (3a), and the second shield (3b) is spaced apart from at least one of the surface electrodes (1a,1b), wherein the second shield (3b) overlaps with the first shield (3a) in a direction perpendicular to the surface electrodes (1a,1b) such that for particle currents parallel to the surface electrodes the first shield (3a) is shielded by the second shield (3b). [12] Method according to claim 11, characterized by , that in process step C the coating is carried out by means of chemical vapor deposition, in particular by means of plasma-enhanced chemical vapor deposition. [13] Use of an electrode arrangement according to any one of claims 1 to 10 for coating a workpiece, in particular by means of chemical vapor deposition.

Images